Editing: Punctuation

The ultimate goal of many language arts teachers is to get their students to write with zero grammar, punctuation, or spelling errors. Little did we realize how lofty a goal this actually is! As soon as students focus on spelling, their comma use disintegrates. Once we get them to look at grammar, their spelling becomes atrocious. It seems to be a never-ending cycle in which they slowly (but surely) improve. Here are some common errors made in punctuation.

Punctuation

Comma	Period & Semicolon	Parentheses & Dashes

Comma Usage

Comma Commas are very productive in the English language. This means that the comma serves a variety of purposes in making written language more understandable. Because commas are used in so many ways, the most common error is to use only commas instead of semicolons, colons, parentheses, dashes and the like. Here are the main rules for using commas and some examples.

Making Lists

The most common example of using commas is when writing a list. A comma is placed after each item in the list, except before "and" and the last item in the list. The list may end the sentence, or be in the middle of a sentence.

At the store I bought butter, eggs, milk and cheese.
I read books by Hemingway, Steinbeck and Joyce in my English class.

Adding information

Commas are used to set off additional information about an object or person in the sentence, but that isn't necessary to understanding the sentence itself. When this additional information is in the middle of the sentence, there are commas before and after the addition. When commas are used for this purpose, they always come in pairs: one before and one after the additional information.

I saw John, wearing an ugly gray T-shirt, at the mall yesterday.
I bought a dog, a cuddly black Lab, for my brother.

Subordinating Clauses

Complex sentences are usually made up of two or more clauses. When one clause is less important to the sentence, then it is the subordinating clause. If the subordinating clause is the first part of the sentence, it is followed by a comma before the main clause. There are a group of words that identify subordinating clauses: while, since, before, after, etc.

While I am happy I don't live with my parents, dorm life is not for me either!
Since we started this semester, I haven't missed a homework assignment.
Before I went to the interview, I prepared answers to possible questions.

If the subordinating clause is the second part of the sentence (it follows the main clause) then there is no comma needed between the two clauses.

I haven't missed a homework assignment since we started this semester.
I prepared answers to possible questions before I went to the interview.

Periods and Semicolons

Periods

Period A period is used at the end of a sentence to signal the end of a complete thought. This punctuation is most often used correctly, but its absence creates a run-on sentence where two main clauses are combined in a single sentence. Main clauses don't like to share attention equally, so each sentence should only have one main clause!

My favorite TV show is Monk.
*My favorite TV show is Monk I also really like Psych. (Incorrect)

Semicolons

When we want two main ideas to be in the same sentence for emphasis, then we use a semicolon to connect the two sentences into one sentence. The semicolon takes the place of the period that would normally follow the first sentence but holds the two clauses together forcing them to share the attention equally. Using semicolons is a stylistic choice and is used only on occasion in order to add emphasis to the relationship between the two ideas.

My favorite TV show is Monk; I also really like Psych.
I just reread my favorite book; I want to be an author someday.

Parentheses and Dashes

Sometimes additional information is of equal importance to the reader as the sentence surrounding it. Sometimes the information is less important to the reader than the sentence and sometimes it is more important. When the information is of equal importance, we use commas to add information.

Parentheses

If the information is less important to the reader than the surrounding sentence, the parentheses set off the information. Parentheses indicate to the reader that the phrase inside them is not incredibly important to understanding the sentence. The reader can then choose whether to read the information or to skip it for the sake of time.

I ran into my brother (he's such a nerd) at school today.

Dashes

Dash Dashes are used to identify the added information as very important and worthy of the reader's time. Dashes set off the additional information so that it pops out to the reader and helps the reader pay attention to that information.